merous types of Cycloïdians and Ctenoïdians, which are almost contemporaneous, are descended from the Placoïdians and Ganoïdians. This would be, in fact, to say, that Mammalia, and thus man, are directly descended from the fishes. All these species have a fixed time of appearance and disappearance; indeed, their existence is limited to a definite period. Nevertheless, they present, in their general character, affinities more or less close, and a definite coördination in a given system, intimately connected with the mode of life of each type, and even of each species. More than this, in all ages, an invisible thread runs through this immense diversity, presenting to us, as a definite result, a continual progress in this development, of which man is the end, the four classes of vertebrated animals the intermediate steps, and the invertebrata the constant accessory accompaniment. Have we not here the manifestations of a mind as powerful as prolific ?-the acts of an intelligence as sublime as provident?-the marks of goodness as infinite as wise?-the most palpable demonstration of the existence of a personal God, author of all things, ruler of the universe, and dispenser of all good? This at least is what I read in the works of the creation, in contemplating them with a grateful heart. Such feelings, moreover, dispose us better to fathom the truth, and study it for itself; and it is my conviction, that if, in the study of the natural sciences, these questions were less avoided, even in the sphere of direct observation, our progress would be generally more sure and more rapid."

It is not astonishing that such results, accompanied by views so wide, and presented with the irresistible force of a profound conviction, gained for their author the respect of the scientific world. Learned societies vied in showing their sympathy with him; and, (a distinction then unparalleled,) at the age of thirty-four, Agassiz was a member of every scientific academy in Europe.

England was, at that time, in advance of all other nations in the study of Geology. It was here that Agassiz found at once the richest materials and the greatest encouragement. Whole collections were put at his disposal, and he obtained in this manner many precious specimens. Some of his friends. recollect with pleasure the impression produced by his visit on the naturalists of the United Kingdom. Several universities were desirous of numbering him among their professors, and the cities of Edinburgh and Dublin, beside conferring on

him the degree of LL. D., enrolled him also among their citizens. We learn that his personal influence induced several persons of high rank to engage in the study of Natural History-among others, Sir Philip Egerton and Lord Enniskil len, whose collections are known to all paleontologists. He became intimate with the most influential persons in the kingdom; he was the welcome guest of Sir Robert Peel and Lord Egerton, and the friend of Buckland, Owen, Murchison, and other distinguished English naturalists.

Having obtained from the study of Fossil Fishes results so important to the history of the development of the whole creation, Agassiz naturally sought to confirm them by the study of other classes of animals, and, accordingly, applied himself to the examination of the Mollusca and the Echinodermata. The latter had been, in general, somewhat neglected by naturalists; the fossil species, in particular, were scarcely known, although, from their great variety, and the complicated structure of their shells, they are of great importance in determining the age of various deposits.

In a short time, he had collected a considerable number of species, belonging to various public and private collections throughout Europe, and in 1836 he published, in the first volume of the Mémoires de la Société des Sciences Naturelles de Neuchâtel, a Prodromus of the class of Echinodermatathe principles of which have since been generally adopted. The same volume contains another paper, giving descriptions and figures of the fossil Echini belonging to the Neocomian group of the Neufchatel Jura. A year afterwards, he published, in another periodical,-(the Mémoires de la Société Helvétique,)-descriptions of the fossil Echini peculiar to Switzerland. In the same year appeared the first number of a more extensive work, having the title of "Monographies d'Echinodermes.” This number contained the monograph of the Salenia, small Echini belonging to the chalk. was followed by three others, treating of the Scutellæ, the Galerites, and the anatomy of the Echinus,-the last number edited by M. Valentin. To facilitate the study of these curious animals, so important to the history of successive creations, Agassiz made casts in plaster of all the specimens in his possession. This collection comprises casts of nearly five

It

* A formation_belonging to the lower green-sand, near Neufchatel, from the Latin name of which city it derives its name.

hundred species, the counterparts of which are to be found in the great museums in Europe, and has thus become one of the most precious documents we possess concerning this class of animals.

The labors of Mr. Agassiz on Fossil Shells are not less important. A young Swiss geologist, M. Gressly, had made a considerable collection of fossil shells from all the stages of the oolitic and cretaceous formations. Mr. Agassiz commenced the publication of them in a work entitled "Etudes critiques sur les Mollusques fossiles du Jura et de la Craie." Of this, four numbers have appeared, with a hundred quarto plates, comprising the group of the Trygonia and that of the Myo. At the same time Agassiz published a German translation of Buckland's Geology, with numerous notes and additions, and revised the French and German translations of Sowerby's Mineral Conchology.

But whatever may be any man's ability and energy, Nature has fixed certain limits to what it is possible for him to accomplish, which he cannot pass. Thus, in order to explain the rapid succession, at so short intervals, of the works we have mentioned, and those of which we have yet to speak, we must observe, that about this time, (1837,) Agassiz associated with himself a young naturalist, Mr. Desor,-who has ever since labored with him and under his direction, and who, having accompanied him in all his Alpine excursions, and in his visit to this country, is now living among us. To the information personally furnished by Mr. Desor, as well as to his writings, we are indebted for much of the present sketch, which could not have been written without his assistance.

The united labors of the two friends accomplished what would have been beyond the reach of a single individual, and the fruits of these labors we see in these numerous publications.

The reputation of Mr. Agassiz, and his unwearying energy, transformed the little town of Neufchatel into a nursery of science to the great astonishment of the peaceful burghers, who, for the most part, could not at all comprehend what was going on around them. But the more enlightened among them soon gathered about him, and thus a Society of Natural History was formed, that soon drew attention by its activity. The Museum, established by the liberality of some of the citi zens, increased rapidly. At the recommendation of Mr. Agassiz, a young naturalist, a pupil of his, Mr. Tschudi,

since known by his work on Peru,-was despatched on a voyage round the world, to collect objects of Natural History.

The influence which Agassiz exercised was not confined to the town where he lived. He succeeded also in reviving the zeal of the "Société Helvétique des Sciences Naturelles," of which he was one of the directors. It was in consequence of his exertions that this society resumed with renewed vigor its publications, which had languished for some time for want of nourishment.

His studies of the Fossils did not make Agassiz forget the Fishes, which have always been, and still are, his favorites. He continued to collect materials for his "Natural History of the Fresh-water Fishes of Europe." His portfolios now contained a complete series of drawings, executed with the greatest care by Mr. Dinkel, the skilful draughtsman whom he had educated at Munich. Having formed at Neufchatel a lithographic establishment, in which there were several distinguished artists, he determined to commence the publication of his work. The plates of the magnificent Atlas-which justly ranks among the first works in this department*--were struck off under his eye at Neufchatel. It is on this account only the more to be regretted, that, after having exhausted all his pecuniary resources, to make this publication worthy of its name, the author found it impossible to continue it on the plan projected. Nevertheless, science has been partly indemnified by the publication of the Embryology of the Salmon tribe, which forms the second number of the work.

After the attention which German naturalists had given to the study of this important and interesting branch of science, Agassiz determined that his Fishes also should contribute their share. He therefore employed his friend, Mr. Vogt, (now Professor of Zoology at the University of Giessen,) who, under his direction, elaborated this part of the work, which is justly esteemed by all physiologists. A third part of the same work, -the Anatomy of the Salmons,-the fruit of the joint labors of Messrs. Agassiz and Vogt, has since appeared in the third volume of the Memoirs of the Neufchatel Society, with a large number of admirably executed plates.

Mr. Agassiz had finished the publication of the "Fossil

*We may add, that, in the opinion of Mr. Agassiz, the execution of these plates has been surpassed only in one work, the Ichthyology of the United States Exploring Expedition.

Fishes." But though the book was finished, the subject was not exhausted. Numerous contributions poured in from all quarters. The study of the Devonian system, in particular, had made known a whole ichthyological fauna of a peculiar character. Mr. Agassiz was requested by the British Association to publish these interesting remains. This he did in a First Supplement to the "Poissons Fossiles"-under the name of the "Fishes of the Devonian System." About the same time he presented to the British Association his Report on the Fishes of the London Clay.

After the publication of the "Fresh-water Fishes," there appeared a work of a different character, and which of itself would be sufficient to establish the reputation of a naturalist. This is the "Nomenclator Zoologicus"-an enumeration of all the genera in the animal kingdom, with an indication of the etymology of their names,-of the author by whom the names were proposed,-the date of their publication,—and the family to which they should be referred.

From the commencement of his career, Agassiz had been struck by the disorder that pervaded zoological nomenclature, and the confusion resulting from the application of the same name to totally different animals. To remedy this difficulty, he prepared registers, in which he entered the names of all animals as they occurred to him in his studies. After having continued this practice for more than ten years, he arranged the names methodically, and published the nomenclature of each class separately, after having it revised by the naturalists most distinguished throughout Europe in each special branch. The Nomenclator Zoologicus is preceded by an introduction in Latin, in which the general principles of nomenclature are profoundly discussed, and it has become an authority universally acknowledged. In connection with this work we must mention another publication, more extensive and not less important the "Bibliographie générale d'histoire naturelle;' which grew up in a similar manner by the side of the Nomenclator. It contains a list of the authors cited in the former work, with bibliographical notices, and is in course of publica tion, at the expense of the Ray Society. This work will form several large volumes;-the first numbers, containing a list of the publications of scientific institutions, have recently appeared.

We come now to speak of a series of discoveries which have particularly tended to make the name of Agassiz known to the